﻿THE 
  LINGERING 
  DRYAD 
  HEYL 
  209 
  

  

  Perhaps 
  the 
  vitalist 
  himself 
  may 
  not 
  reaHze 
  it, 
  but 
  to 
  the 
  student 
  of 
  

   the 
  philosophy 
  of 
  history 
  this 
  vague 
  ' 
  ' 
  difference 
  in 
  kind 
  ' 
  ' 
  suggests 
  the 
  

   last 
  lingering 
  trace 
  of 
  what 
  was 
  once 
  a 
  dryad. 
  As 
  a 
  cloudlet 
  dwindles 
  

   and 
  disappears 
  in 
  the 
  beams 
  of 
  the 
  sun, 
  so 
  the 
  dryad 
  has 
  shrunk 
  to 
  a 
  

   mere 
  wisp 
  of 
  vapor, 
  which 
  with 
  a 
  little 
  more 
  light 
  seems 
  destined 
  to 
  

   disappear 
  forever. 
  

  

  But 
  now 
  that 
  we 
  have 
  finished 
  pointing 
  out 
  the 
  mote 
  that 
  is 
  in 
  the 
  

   biologist's 
  eye, 
  let 
  us 
  examine 
  our 
  own 
  clarity 
  of 
  vision. 
  Are 
  we 
  

   physical 
  scientists 
  in 
  any 
  measure 
  responsible 
  for 
  the 
  lingering 
  of 
  the 
  

   dryad? 
  

  

  By 
  the 
  latter 
  half 
  of 
  the 
  nineteenth 
  century 
  physical 
  theory 
  had 
  

   become 
  a 
  well 
  knit, 
  sharply 
  crystallized 
  and 
  self-sufficient 
  body 
  of 
  

   doctrine. 
  While 
  it 
  was 
  recognized 
  fully 
  and 
  generally 
  that 
  much 
  was 
  

   as 
  yet 
  unknown, 
  it 
  was 
  felt 
  quite 
  as 
  generally 
  that 
  what 
  had 
  been 
  

   established 
  would, 
  with 
  perhaps 
  a 
  little 
  amendment 
  and 
  modification, 
  

   stand 
  forever. 
  The 
  physical 
  theory 
  of 
  the 
  last 
  century 
  was 
  much 
  

   admired 
  by 
  its 
  devotees, 
  upon 
  whom 
  it 
  reacted 
  in 
  turn 
  to 
  the 
  extent 
  of 
  

   making 
  them 
  at 
  times 
  a 
  bit 
  dogmatic. 
  If 
  there 
  was 
  a 
  conflict 
  between 
  

   physics 
  and 
  a 
  sister 
  science, 
  physics 
  must 
  be 
  right. 
  

  

  The 
  classical 
  instance 
  of 
  this 
  attitude 
  is 
  the 
  famous 
  controversy 
  

   over 
  the 
  age 
  of 
  the 
  earth, 
  between 
  the 
  physicists 
  on 
  the 
  one 
  hand 
  and 
  

   the 
  geologists 
  and 
  biologists 
  on 
  the 
  other. 
  Perhaps 
  nothing 
  in 
  the 
  

   annals 
  of 
  nineteenth 
  century 
  physics 
  made 
  such 
  an 
  impression 
  upon 
  

   the 
  sister 
  sciences. 
  This 
  controversy 
  lasted 
  for 
  33 
  years 
  with 
  unabated 
  

   vigor, 
  and 
  was 
  not 
  finally 
  settled 
  until 
  the 
  discovery 
  of 
  radioactive 
  

   substances. 
  

  

  In 
  1862, 
  upon 
  the 
  basis 
  of 
  the 
  laws 
  of 
  the 
  conduction 
  of 
  heat 
  as 
  laid 
  

   down 
  by 
  Fourier, 
  Kelvin 
  calculated 
  that 
  the 
  time 
  that 
  had 
  elapsed 
  

   since 
  the 
  earth 
  had 
  solidified 
  from 
  a 
  molten 
  state 
  could 
  not 
  be 
  less 
  than 
  

   20,000,000 
  or 
  more 
  than 
  400,000,000 
  years. 
  He 
  admitted 
  that 
  

   rather 
  wide 
  limits 
  were 
  necessary, 
  but 
  was 
  inclined 
  to 
  attach 
  more 
  

   weight 
  to 
  the 
  lower 
  figure 
  than 
  to 
  the 
  higher. 
  In 
  this 
  he 
  was 
  con- 
  

   firmed 
  by 
  a 
  similar 
  calculation 
  made 
  by 
  Helmholtz 
  of 
  the 
  age 
  of 
  the 
  

   sun. 
  

  

  At 
  this 
  estimate 
  biologists 
  and 
  geologists 
  stood 
  aghast. 
  The 
  pros- 
  

   pect 
  of 
  having 
  to 
  pack 
  into 
  a 
  paltry 
  400,000,000 
  years 
  the 
  whole 
  

   progress 
  of 
  organic 
  evolution 
  from 
  amoeba 
  to 
  man 
  seemed 
  to 
  biologists 
  

   unreasonable. 
  And 
  with 
  the 
  geologists 
  the 
  situation 
  was 
  still 
  worse. 
  

   It 
  was 
  generally 
  recognized 
  that 
  a 
  very 
  long 
  period 
  of 
  time 
  must 
  have 
  

   elapsed 
  after 
  solidification 
  before 
  life 
  of 
  the 
  most 
  primitive 
  form 
  made 
  

   its 
  appearance, 
  and 
  this 
  period, 
  in 
  addition 
  to 
  that 
  required 
  by 
  evolu- 
  

   tion, 
  must 
  be 
  made 
  to 
  fit 
  Kelvin's 
  Procrustean 
  bed. 
  Moreover, 
  it 
  was 
  

   felt 
  by 
  geologists 
  that 
  such 
  a 
  view 
  involved 
  a 
  return 
  to 
  eighteenth 
  

   century 
  ideas, 
  from 
  which 
  geology 
  was 
  just 
  beginning 
  to 
  emerge. 
  

  

  